Refrigeration compressor



April 3, 1956 R. BENSON ETAL 2,740,578

REFRIGERATION COMPRESSOR Filed Feb. 24, 1953 2 Sheets-Sheet l INVENTORS. RALPH L. BENSON. NORBERT A. SCHERZINGER BY I z/m 7W2 ATTORNEYS.

April 3, 1956 R. L- BENSON ETAL 2,740,578

REFRIGERATION COMPRESSOR Filed Feb. 24, 1953 2 Sheets-Sheet 2 IN V EN TORS.

RALPH L. BENSON. NORBERT A. SCHERZINGER BY dim/(9. Q 444! Zc/W KIA/-22.

ATTORNEYS.

United States Patent REFRIGERATION COMPRESSOR Ralph L. Benson and Norbert A. Scherzinger, Cincinnati, Ohio, assignors to Avco Manufacturing Corporation, Cincinnati, Ohio, a corporation of Delaware Application February 24, 1953, Serial No. 338,202

7 Claims. (Cl. 23058) The present invention relates to a refrigeration compressor of the type used for compressing and circulating refrigerant within the closed system of a domestic refrigerator or home freezer. The invention relates more particularly to a compressor which is compact and well adapted for use in modern domestic refrigerators. Further, in accordance with this invention a single basic compressor structure may be easily modified to produce units having different pumping capacities and horsepower ratings.

With the advance of modern refrigeration has come the persistent demand for more compact compressors. This is particularly true of the compressors used in domestic refrigerators since the outside dimensions of refrigerators are relatively fixed and increase of useful voltime can only be obtained through more compact accessories and judicious use of the space within the cabinet. Gne difficulty that has faced the refrigeration industry for years is the large size of the compressor which frequently is as much as ten inches in diameter and nine inches high. To accommodate a compressor of this size, it is necessary to provide an undesirably large machine compartment either below or above the food storage volume of the refrigerator. It is recognized that such a machine compartment represents an inefficient use of space, and a demand has arisen for a more compact compressor which can be mounted closely adjacent the refrigerator liner, making possible a marked reduction in the size of the machine compartment and an increase in the food storage volume within the cabinet. Through the present invention, such a compact compressor has been made available to the industry without sacrifice of any of the advantages which characterize the conventional modern compressor.

Another difficulty confronting the industry concerns the need for different size compressors for use in various model refrigerators. The typical modern manufacturer produces a complete line of refrigerators ranging from small size cabinets to relatively large cabinets of 12 cu. ft. capacity or more. In the interest of operating ciliciency and cost reduction, it is desirable to use the smallest size compressor that has adequate capacity for the refrigeration needs of the cabinet. This has necessitated the production by each manufacturer of a number of compressors, each compressor being different in its basic dimensions and requiring an extensive amount of individual tooling. In addition to its other benefits, the present invention also has solved this difficulty and has made it possible, by minor variations in an otherwise standardized compressor, to produce units of different horsepower and pumping capacities.

Briefly stated, the present invention comprises a compressor housing within which is sealed an electric motor including a stator and a rotor, the rotor being secured for conjoint rotation to a vertical crankshaft. The crankshaft includes an eccentric which is in driving engagement with a connecting rod, the connecting rod imparting reciprocating motion to a piston slidably supported 2,740,578 Patented Apr. 3, 1956 in a cylinder located closely adjacent to, but on the outside of and partially overlapping, the motor stator. The stator and crankshaft are both supported through a common frame one side of which is cut away for passage of the connecting rod closely beneath the stator. The cut away portion of the frame also facilitates assembly of the crankshaft and connecting rod.

Because of the cylinder location beyond the outside diameter of the stator, it is possible to increase the bore of the cylinder without interfering with the stator and without change of the piston and connecting rod center line location. Thus, change of the cylinder bore to produce compressors of different pumping capacities does not necessitate major redesign of the frame, connecting rod, crankshaft, and other compressor components.

In view of the foregoing, it will be appreciated that a broad object of this invention is to provide an improved refrigeration compressor.

More specifically, it is an object to provide a compressor which is extremely compact and which has a relatively small over-all height.

Another object of the invention is to produce a refrigeration compressor constructed and arranged to facilitate change of pumping capacity without major redesign.

Still more specifically stated, it is an object of the present invention to provide a compressor in which the compressor cylinder is located outside of the motor stator, the cylinder being so arranged that an associated piston and connecting rod can be located closely adjacent the stator, thereby conserving space and reducing the over-all dimensions of the compressor.

Another object of the invention is to provide a motor frame which is cut away at one side to permit passage of the connecting rod closely adjacent to the motor stator which is supported by and mounted in the motor frame.

The novel features that are considered characteristic of the invention are set forth in the appended claims; the invention itself, however, both as to its organization and method of operation, together with additional objects and advantages thereof, will best be understood from the following description of a specific embodiment when read in conjunction with the accompanying drawings, in which:

Figure 1 is a vertical cross sectional view, taken through the center of the assembled compressor, showing the relative disposition of the motor, motor frame, compressor cylinder, and related components;

Figure 2 is a bottom plan view showing the underside of the compressor with its bearing support plate removed, the lower half of the compressor housing being removed in this view to simplify the illustration;

Figure 3 is a bottom plan view of the bearing support plate designed for attachment to the bottom of the compressor; and

Figure 4 is a fragmentary view illustrating a resilient spring mounting for supporting the compressor within its housing.

The basic structural component of this compressor is the motor frame, generally designated 1, which defines a cylindrical bore 2 into which is force-fitted stator 3 of an electric motor, generally designated 4. Cooperating with the stator is a rotor 5 which is force-fitted on a vertically disposed crankshaft 6. The crankshaft is supported in vertically aligned plain bearings 7 and 8, bearing 7 being formed in the motor frame 1, and bearing 8 being formed within a bearing support plate 9. This support plate is bolted, as at 10, to face 11 formed on the bottom of frame 1.

Crankshaft 6 includes upper and lower journals 12 and 13 cooperating with bearings 7 and 8, respectively. Intermediate the journals is formed an eccentric 14 which engages connecting rod 15. The connecting rod is pivotally attached to a piston pin 16 which in turn is secured within piston 17. The piston is slidably supported by cylinder 18 which is formed integrally with the motor frame 1.

Cylinder 18 defines a cylindrical bore 19 Which is disposed perpendicularly to the axis of crankshaft 6. Cylinder head 20 and valve plate 21 are bolted to the outer end of cylinder 18 in position to seal the cylinder and provide the necessary valve action for compressor pumping operation.

The bearing support plate 9 defines a lower fiat face 22 to which is secured a thrust plate 23 which acts as a thrust bearing and support for the lower end of crankshaft 6. The thrust plate is fully illustrated in Figure 3.

Particular attention should be directed to the formation of motor frame 1. With reference to Figures 1 and 2, it will be noted that the frame is formed to define a somewhat hemispherical wall 24 which extends from the bearing 7 downwardly and outwardly beneath stator 3, the wall joining integrally with an outer wall section 25 in the upper portion of which is formed bore 2 for receiving the stator.

With particular reference to Figure 2, it will be noted that the hemispherical wall 24 is cut away locally at 26 to permit passage of connecting rod 15. The cutout extends completely through the bottom of the frame to permit assembly of the connecting rod and crankshaft, as will be more fully described later. After assembly of these components, the lower bearing support plate is bolted to the bottom of the motor frame.

Attention should also be directed to the location of the cylinder 18 which is formed integrally with the motor frame. It is to be noted that the bore 19 is located on the outside of the stator periphery and that no part of the bore is beneath the stator. Instead, the bore overlaps the vertical dimension of the stator somewhat as indicated at .27. By locating the cylinder bore outside of the stator, it is possible to position the connecting rod so that it passes closely beneath the stator, as illustrated particularly well in Figure 1. This construction reduces the over-all compressor height so that the completely assembled compressor has an over-all vertical dimension of less than seven inches. As has already been discussed, this is highly desirable in a refrigeration compressor.

The procedure for assembling the compressor is as follows: The motor frame 1 is inverted and the piston, with assembled connecting rod, is introduced into the bore 19, the connecting rod extending through cutout 26. The crankshaft is then dropped through bore 14a of the connecting rod and journal 12 is inserted into bearing 7. The lower bearing support plate 9, with thrust plate 23 attached, is then bolted to face 11 of the motor frame 1. When the assembly has reached this stage, the other compressor components, such as cylinder head 20 and valve plate 21 may be mounted on the motor frame. The partial assembly may then be checked for operation and pumping capacity. After the conclusion of such tests, stator 3 and rotor may be force-fitted within frame 1 and on crankshaft 6, respectively.

It will be noted from Figures 1 and 2 that the compressor assembly is sealed within a split housing 28. In the preferred embodiment this housing constitutes a low side dome from which gaseous refrigerant is drawn by the compressor in the course of its operation, as will be described more fully hereinafter.

It is to be noted that a plurality of springs may be provided for supporting the assembled compressor on lower half 29 of the housing. Mounting pads 30a are formed on frame 1 for attachment of the supporting springs. The details of a typical spring installation are shown in Figure 4 which illustrates a vertical coil spring 30 engaging upper and lower spring retainers 31 and 32, respectively. Retainer 32 is spot welded to the lower half of the casing 29, while the upper retainer is bolted to the motor frame 1, as at 33.

After the compressor assembly is attached to its various points of spring suspension, upper half 34 of the housing is welded to the lower half, as at 35.

During operation, the stator 3 is energized from a suitable source of electrical energy, thereby producing rotation of crankshaft 6 and reciprocation of piston 17 by virtue of the connecting rod 15 which transfers motion from eccentric 14 to the piston. As the piston reciprocates, valves (not shown), cooperating with valve plate 21, admit gaseous low pressure refrigerant to the cylinder and, at the end of the compression stroke of the piston, control the discharge of compressed refrigerant to a discharge muffier 36 (see Figure 2). The low pressure refrigerant is aspirated by the compressor through an inlet muffler 37 and an intake pipe 38. The compressed refrigerant flows from muffler 36 into a discharge line 39 which passes through the side wall of the housing and conveys the refrigerant to the condenser (not shown) of the refrigerator, or home freezer, in which the compressor is installed.

It is necessary to provide lubrication for the bearings of the compressor. Various pumping devices may be used for this purpose, although it has been found that adequate lubrication can be supplied through the provision of a shallow recess 40 in the lower end of crankshaft 6. Oil, which normally fills the compressor hous-' ing to the level of the connecting rod, flows through hole 41 of thrust plate 23 into recess 40. The centrifugal forces acting on the oil within the recess develop a pressure head at the periphery of the recess which forces oil through a plurality of vertical ducts (not shown) formed in the crankshaft. The ducts communicate with discharge ports, such as 42, which supplies oil to hearing 7, and 43 which supplies oil to the eccentric 14.

In order-to prevent passage of foreign particles into the lubrication system, a fine mesh screen 44 may be bolted to the lower face of the bearing support plate 9 in position to surround thrust plate 23. Thus, all oil flowing to hole 41 is strained.

Because of the location of the cylinder bore outside of the stator, it is possible to enlarge its diameter to produce compressors having different pumping capacities. The following chart illustrates the combination of bore, stroke, and refrigerant used in compressors of the various horsepower ratings indicated.

Bore H. P Diameter, stmke' Refrigerant inches ch65 9t 1 %3 Freon F-12. 5t. 1%; Win Freon F-l2. 1%; n Freon F22. 1%: Freon F-22. 1% s s Freon F-12. 1-360 Freon F622.

It will be noted that the various bores can be used without change .of connecting rod location since the bore, as it is enlarged, may overlap the stator. In prior art compressors, in which the bore was located immediately beneath the stator, any increase in diameter necessitated a relocation of the connecting rod with a consequent redesign of all of the major components of the compressor. Through the present design this diificulty has been eliminated.

Thus, in accordance with the present invention, the bore of the compressor can be changed as desired with no redesign of the motor frame, bearing support plate, connecting rod, or crankshaft. Further, use of different refrigerants, such asvFreon F-l2 and F-22, increases the horsepower range of the compressor without further change of the diameter of the bore. This represents a great advance in the art of compressor construction.

In view of the foregoing description, it will be appreciated that-an improved refrigeration compressor has been provided and one which is very compact and which is easily arranged for different pumping capacities without major redesign.

Having described a preferred embodiment of our invention, we claim:

1. In a refrigeration compressor, a main frame formed to define an upright central bore, a motor stator fitted within the bore, said frame beneath the bore being formed to define a bearing centrally positioned relative to the bore, a crankshaft rotatably supported by said bearing, a rotor secured to said crankshaft, said frame defining a cylinder bore vertically overlapping but laterally outside of said stator, a piston in the cylinder bore, and a connecting rod extending between said piston and said crankshaft.

2. Apparatus as defined in claim 1 in which said frame is locally cut away adjacent the cylinder bore to form a clearance space for passage of said connecting rod.

3. In combination in a refrigeration compressor a unitary frame, an upright stator secured to said frame, a rotor within said stator, a crankshaft coaxially positioned by said frame within said stator, said rotor being secured to said crankshaft, said frame including a cylinder bore vertically overlapping and laterally outside of said stator, a piston slidably supported by the cylinder bore, and a connecting rod articulately secured to said piston and said crankshaft.

4. In combination in a refrigeration compressor, a unitary frame formed to define a cylindrical bore and a bearing centrally disposed beneath the bore, a stator secured within the bore, a crankshaft rotatably supported by the bearing, a rotor within said stator secured to said crankshaft, said frame defining a cylinder bore a diameter of which partially overlaps said stator, a piston slidably supported by the cylinder bore, and a connecting rod interconnecting said piston and said crankshaft.

5. Apparatus as defined in claim 4 in which said frame is locally cut away between said crankshaft and the cylind2 bore to permit passage of said connecting rod closely beneath said stator.

6. In combination in a refrigeration compressor, a frame defining an upright cylindrical bore and including a hemispherical wall centrally disposed beneath the bore, said hemispherical wall defining a bearing, a stator secured within said cylindrical bore, a crankshaft supported in part by the bearing centrally of said stator, a rotor within said stator secured to said crankshaft, a bearing support plate secured to the bottom of said frame and including a second bearing for supporting said crankshaft, said frame defining a cylinder vertically overlapping and laterally outside of said stator, a piston within the cylinder, and means for transferring motion from said crankshaft to said piston.

7. In combination in a compressor, a frame, a stator supported by said frame, a rotor centrally disposed within said stator, a crankshaft secured to said rotor and extending below the lower extremity of said stator, means on said frame for rotatably supporting said crankshaft, a cylinder connected to said frame and located outside of said stator, a diameter of said cylinder partially overlapping said stator, a piston slidably supported by said cylinder, and means passing in an air space bounded in part by said frame and in part by said stator for transferring motion from said crankshaft to said piston.

References Cited in the file of this patent UNITED STATES PATENTS 868,362 Priest Oct. 15, 1907 1,470,548 Spohrer Oct. 9, 1923 1,636,001 Kasley July 19, 1927 2,019,689 Marbury Nov. 5, 1935 2,505,709 Goldberg et al May 3, 1944 2,605,044 Hill July 29, 1952 2,638,264 Browne May 12, 1953 FOREIGN PATENTS 6,032 Great Britain Mar. 10, 1910 488,481 Germany Dec. 30, 1929 

